Cam for square-hole drills.



G. E. OTIS.

CAM FOR SQUARE HOLE DRILLS.

APPLICATION FILED JAN. 19, I918.

Patented Dec. 31, 1918.

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Application filed January 19, 1918.

To all whom it may concern:

Be it known that I, GERALD E. OTIS, a citizen of the United States of America, and a resident of Buffalo, Erie county, and State of New York, have invented certain new and useful Improvements in Cams for Square- Hole Drills, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof.

My invention relates to cams for square hole drills and its object is to provide an improved form of cam which may be used to cause a hole of a desired size to be drilled when used with a cam guide of predetermined transverse dimensions.

Another object is to provide cams of different dimensions and forms for use \with the same drill cam-guide or with cam guides of the same transverse dimensions for drilling square holes of different transverse dimensions.

More especially its object is to improve upon the cam shown and described in my allowed application for patent, Serial No. M2582, filed by me January 17, 1917,. by providing a formula for forming cams which embody the invention covered by this copending application by the use of which cams for desired purposes may be quickly and accurately laid out.

In order that my invention may be thor oughly understood, I will now proceed to describe the same in the following specification and then point out the novel features thereof in appended claim.

Referring to the drawings:

Figures 1 and 2 are diagrammatic plan views of square hole drill cams and their surrounding guides, with my improved construction formula shown in conjunction therewith.

I have found that a satisfactory cam made in accordance with the invention described and claimed in the aforesaid application for Patent Serial No. 142,882 may be built up about an isosceles triangle of which the base is 50% greater than the height, and that the height of such a triangle will be of the same dimension as that of the side of the drilled hole. Another fact is that the point in the center Of the perpendicular to the base of the lines CAM FOR soUARn-HoLn'DRILLs.

' 's eiiiicatiiiii.ciirlette s Patent; Patented Dec. 3 1, 1918.

Serial No. 212,558.

such triangle will be the center of the cam and of the cam guide. It is also true that the size of the guide is not important provided that the sides of the holes to be drilled are less than two-thirds the sides of the cam.

Let us assume that the cam guide is a square of two inch sides. This is shown in the drawings on an enlarged scale by broken lines designated by the reference letter (i. Through the center of the sides of the square the construction lines M, N are drawn. At a distance one-half the side of the hole to be drilled, which I will call S, a line 0 is drawn parallel with the line N and a point P marked on the line M a distance 2 the other side of the line N. On the line 0 the points Q and R are marked, each a} S from the line M. Lines T and U are then drawn through the points P, Q and P, B respectively. This completes the triangle about which the cam curves are to be drawn with that part of the line 0 which is between the points Q, and R and of a length of 1% S as its base, shown in inverted position in the drawings.

With the point P as a center, the cam curve D or D is drawn tangent to the opposite side of the square G to the parts of T and U which extend beyond the triangle.

With the point Q as a center the cam curve E or E is drawn tangent to the opposite side of the square G to the produced lines 0 and T.

With the point R as a center the cam curve 15 or F is drawn tangent to the opposite side of the square G to the produced lines 0 and U.

The cam curves K, L and I or K L and I are drawn from the centers Q, R and P respectively to complete the periphery of the cam.

In Fig. 1 the cam is shown designed to move a drill bit in such a path as to cut a one inch square hole and in Fig. 2 the proportions are such as to cause a one-half inch square hole to be out. Any desired square hole may be drilled with a guide of given size by the use of this invention up to two thirds of the size of the guide.

What I claim is:

A cam for square hole drills for a square guide of given dimensions which is conand the center of a perpendicular line from structed by describing arcs of circles from said base to its opposite apex in the center the apexes of an isosceles triangle drawn of said square, and with three of said arcs 10 Within a square corresponding With the size tangent to the sides opposite their centers. l

of the guide, having its base one and one- In witness whereof, I have hereunto set half times the size of the hole to be drilled my hand this 14th day of January, 1918. and parallel With one side of-said square GERALD EARLE OTIS.

Copies of this patent may be obtained for five cents each, by addressing the "Gommluloner of Patents, Washington, D. 0." 

